Projection device for smart glasses, method for displaying image information with the aid of a projection device, and control unit

ABSTRACT

A projection device for smart glasses. The projection device includes an image-generation unit for generating at least one first ray of light representing first image information, and a second ray of light representing second image information. The first ray of light and the second ray of light differ from each other with regard to a beam divergence. In addition, the first image information and the second image information differ from each other with regard to a perceivable image sharpness. Moreover, the projection device includes at least one deflection element, which is configured to display the first image information within a first field of view of an eye using the first ray of light, and to display the second image information within a second field of view of the eye disposed outside the first field of view, using the second ray of light.

FIELD OF THE INVENTION

The present invention is based on a device or a method according to thedefinition of the species in the independent claims. A computer programis also a subject matter of the present invention.

BACKGROUND INFORMATION

Smart glasses for superimposing information in a field of view of a userare believed to be understood.

SUMMARY OF THE INVENTION

Against this background, the approach presented here introduces aprojection device for smart glasses, a method for displaying imageinformation with the aid of a projection device, and furthermore, acontrol unit that uses this method and finally a corresponding computerprogram according to the main claims. The measures indicated in thedependent claims allow for advantageous further developments andimprovements of the device indicated in the independent claim.

A projection device for smart glasses is introduced, the projectiondevice having the following features:

An image-generation unit for generating at least one first ray of lightrepresenting first image information, and a second ray of lightrepresenting second image information, the first ray of light and thesecond ray of light differing from each other with regard to a beamdivergence, and the first image information and the second imageinformation differing from each other with regard to a perceivable imagesharpness; and

at least one deflection element, which is configured to display thefirst image information within a first field of view of an eye using thefirst ray of light, and to display the second image information within asecond field of view of the eye using the second ray of light, thesecond field of view being disposed outside the first field of view.

Smart glasses may be understood as glasses for the display of visualinformation in a field of view of a wearer of the smart glasses. An itemof visual information, for example, may be understood as an image pointor as image content. Depending on the embodiment, the first or thesecond image information may represent a monochromatic or color image.The two items of image information, for example, may represent one andthe same image content at different virtual image distances, and thus atdifferently perceived image sharpnesses. That is to say, the first imageinformation may involve an image that is perceived as being in focus,and the second image information may be an image that is perceived asbeing out of focus. The two rays of light may be a laser beam(monochromatic image display) or a plurality of approximatelysuperimposed laser beams (multi-color display) in each case. The imagesharpness is no physical property of the ray of light but a consequenceof the distance between the eye of the observer and the distance of thevirtual image. For example, the first ray of light displays a virtualimage at a great distance while the second ray of light may represent animage on the plane of an eyeglass lens. Because of the short distancefrom the eye, this second image is unable to be displayed sharply.

A deflection element may be understood as an element for deflecting thefirst and the second rays of light. More specifically, the deflectionelement may be a hologram or a mirror. Conceivable, for instance, arealso other methods of action. For example, the deflection element mayalso be realized as an optical phase array, an electro-optical or amagneto-optical deflector or as an array of such deflectors. Thedeflection element, for example, is able to be integrated into aneyeglass lens of the smart glasses. Depending on the specificembodiment, the deflection element may have at least a first deflectionsection for deflecting the first ray of light into the first field ofview, and a second deflection section for deflecting the second ray oflight into the second field of view. The deflection sections may behologram or mirror layers, for instance. A field of view may beunderstood as a range that is perceivable by an eye of the wearer who iswearing the smart glasses. The first and the second fields of view mayadjoin each other or may at least partially overlap each other, forexample. In particular, the first field of view may be a central fieldof view of the eye, and the second field of view may be a peripheralfield of view of the eye.

Each ray of light may cover the entire field of view. Only the imageinformation of the second ray of light that is perceived as being out offocus may be able to be selectively deactivated as a function of thegaze direction of the user.

The first ray of light, for example, may also be a beam of rays which ismade up of a plurality of first rays of light. In the same way, thesecond ray of light may be a beam of rays which is made up of aplurality of second rays of light.

The approach introduced here is based on the recognition that smartglasses are able to project images having different degrees of sharpnessinto different fields of view of an eye of an observer with the aid of asuitable deflection element, in particular a holographic opticalelement, for instance. Utilizing the physiology of the human eye, forexample, it is possible to display sharp image content only where it isalso able to be perceived.

This allows for a resource-sparing system design featuring the lowestpossible number of components. For example, the number of required lightsources in a monochrome image display is able to be reduced to two lightsources, and in a full color image display (RGB), it is able to bereduced to six light sources. At two primary colors and the secondarycolors resulting therefrom, even four light sources, for example, may besufficient. As a result, the number of required reflection layers suchas hologram layers may also be reduced in a corresponding manner. At thesame time, the approach presented here allows for the realization ofsmart glasses that have a large field of view and a large effective eyebox. The functionality of the smart glasses is therefore able to beimproved.

According to one embodiment, the image-generation unit may be configuredto generate the first ray of light and the second ray of light in such away that the first image information has a greater perceived imagesharpness than the second image information. The deflection element maybe configured to display the first image information within a centralfield of view of the eye as the first field of view and, additionally oralternatively, display the second image information within a peripheralfield of view of the eye as the second field of view. The first imageinformation may have an image featuring a greater image sharpness. Thedifferent degrees of image sharpness may particularly be created by thevirtual image distance. For example, using a correspondingly powerfulcontact lens for extreme farsightedness, the second image informationmay also be sharply perceivable. A central field of view may beunderstood as a range in which the eye perceives images with high visualacuity, i.e. foveally. A peripheral field of view may be understood as arange in which the eye perceives images with reduced visual acuity, i.e.peripherally. For example, the central field of view may at leastpartially be surrounded by the peripheral field of view. This makes itpossible to display image information of high image sharpness only inthe ranges that the eye is able to perceive, i.e. in which the eye isactually also able to see clearly. This may improve the efficiency ofthe projection device, and the production costs of the projection deviceare therefore able to be reduced.

It is advantageous if the deflection element is configured to displaythe first image information within a first angular range of the firstfield of view allocated to a first position of the eye and, additionallyor alternatively, within a further angular range of the first field ofview allocated to a further position of the eye. An angular range, forexample, may be understood as an eye box having a specific opening anglewithin which the eye is able to perceive the first image information ata certain eye position. Depending on the specific embodiment, theopening angle may be between 5 and 20 degrees, for instance. With theaid of this embodiment, the first image information is able to bedisplayed in different angular ranges in the first field of view.

According to a further embodiment, the deflection element may beconfigured to display the first image information within an angularrange, as the first angular range, that is disposed adjacent to thesecond angular range, or that at least partially overlaps with thesecond angular range. This makes it possible to ensure a display of thefirst image information without any gaps in the first field of view.

In addition, the deflection element may be configured to display thefirst image information within at least one further angular range of thefirst field of view allocated to a further position of the eye. Thisallows the first image information to be displayed in a plurality ofdifferent angular ranges. For example, the angular ranges may bedisposed in the form of a raster for this purpose.

It is also advantageous if the deflection element includes at least onehologram layer for deflecting the first ray of light and, additionallyor alternatively, for deflecting the second ray of light. A hologramlayer may be understood as a holographic optical element that isrealized in the form of a layer. This development allows for a simpleand cost-effective realization of the deflection element.

In addition, the projection device may include at least one furtherdeflection element, which is able to be configured to display the firstimage information within the first field of view using the first ray oflight. In particular, the deflection element may be configured togenerate at least one first eye box for perceiving the first imageinformation within the first field of view. Accordingly, the furtherdeflection element may be configured to generate at least one second eyebox for perceiving the first image information within the first field ofview. The first eye box and the second eye box may in particular bedisposed next to each other. This makes it possible to generate eyeboxes that feature larger angular ranges.

According to a further specific embodiment, the projection device mayhave an eyeglass lens. The deflection element is able to be realized aspart of the eyeglass lens. An eyeglass lens, for example, may be a diskor a lens made of glass or plastic. Depending on the specificembodiment, the eyeglass lens may be shaped in order to correctrefraction errors of the eye. This specific embodiment allows for aparticularly simple, unobtrusive and cost-effective integration of thedeflection element.

The deflection element may extend across at least a main part of asurface of the eyeglass lens. This allows for the largest possiblecoverage of a field of view of the eye by the deflection element.

According to a further embodiment, the projection device may have aneye-position ascertainment unit for ascertaining an eye position of theeye. The image-generation unit may be configured to generate the firstray of light and, additionally or alternatively, the second ray of lightas a function of the eye position. The eye-position ascertainment unit,for example, may include a camera for detecting the eye position. Thisembodiment makes it possible to achieve a display of the first or thesecond image information that is dependent on the eye position and thussaves energy.

In addition, the image-generation unit may be configured to generate thefirst ray of light and, additionally or alternatively, the second ray oflight in such a way that the first image information and, additionallyor alternatively, the second image information represents an at leasttwo-color image. This makes it possible to improve the display qualityof the projection device.

The approach presented here furthermore provides a method for displayingimage information with the aid of a projection device according to oneof the preceding embodiments, the method including the following steps:

Generating the first ray of light and the second ray of light; and

Deflecting the first ray of light in order to display the first imageinformation within the first field of view, and deflecting the secondray of light in order to display the second image information within thesecond field of view.

For example, this method is able to be implemented in software orhardware or in a mixed form of software and hardware, e.g., in a controlunit.

In addition, the approach introduced here provides a control unit, whichis configured to execute, actuate and/or implement in correspondingdevices the steps of a variant of a method introduced here. Thisembodiment variant of the present invention in the form of a controlunit is also able to achieve the objective on which the presentinvention is based in a rapid and efficient manner.

For this purpose, the control unit may include at least one processingunit for the processing of signals or data, at least one memory unit forstoring signals or data, at least one interface with a sensor or with anactuator for reading in sensor signals from the sensor or for outputtingcontrol signals to the actuator, and/or at least one communicationsinterface for reading in or outputting data, which are embedded in acommunications protocol. The processing unit, for instance, may be asignal processor, a microcontroller or the like, and the memory unit maybe a flash memory, an EPROM or a magnetic memory unit. Thecommunications interface may be configured to read in or output data ina wireless and/or a line-bound manner, and a communications interfacethat is able to read in or output the line-bound data may read in thesedata, e.g., electrically or optically, from a correspondingdata-transmission line or output these data onto a correspondingdata-transmission line.

In this context, a control unit may be understood as an electricaldevice, which processes sensor signals and outputs control and/or datasignals as a function thereof. The device may have an interface, whichis able to be configured in the form of hardware and/or software. In thecase of a hardware design, the interfaces may be part of what is knownas a system ASIC, for example, which includes a wide variety offunctions of the control unit. However, it is also possible that theinterfaces are discrete integrated switching circuits or are at leastpartially made up of discrete components. In the case of a softwaredevelopment, the interfaces may be software modules, which are providedon a microcontroller in addition to other software modules, for example.

Also advantageous is a computer-program product or a computer programhaving program code, which is able to be stored on a machine-readablecarrier or memory medium such as a semiconductor memory, a hard diskmemory, or an optical memory, and which is used for executing,implementing and/or actuating the steps of the present method accordingto one of the afore-described embodiments, in particular when theprogram product or the program is executed on a computer or on a device.

Exemplary embodiments of the present invention are shown in the drawingand elucidated in greater detail in the following description.

In the following description of advantageous exemplary embodiments ofthe present invention, identical or similar reference numerals are usedfor the elements that are shown in the various figures and have asimilar effect, while a repeated description of these elements isomitted.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic illustration of a method of functioning of anear-to-eye display of smart glasses.

FIG. 2 shows a schematic illustration of a method of functioning of anear-to-eye display of smart glasses.

FIG. 3 shows a diagram to illustrate a visual acuity as a function of anangle at an optical axis.

FIG. 4 shows a schematic illustration of smart glasses together with aprojection device according to an exemplary embodiment.

FIG. 5 shows a schematic illustration of a projection device accordingto an exemplary embodiment.

FIG. 6 shows a schematic illustration of a system of eye boxes for thedisplay of image information with the aid of a deflection elementaccording to an exemplary embodiment.

FIG. 7 shows a schematic illustration of a correlation between anorientation of an eye and an image position on a deflection elementaccording to an exemplary embodiment.

FIG. 8 shows a schematic illustration of two overlapping angular rangesfor the display of image information with the aid of a deflectionelement according to an exemplary embodiment.

FIG. 9 shows a flow diagram of a method according to an exemplaryembodiment.

FIG. 10 shows a schematic illustration of a control unit according to anexemplary embodiment.

DETAILED DESCRIPTION

FIG. 1 shows a schematic representation of a method of functioning of anear-to-eye display 100 of smart glasses, or in short, an NTE display.Shown is a micro-display as a near-to-eye display 100, which may beviewed via a deflection optics in the form of a prism 102 and a lens104. The field of view, abbreviated: FOV, of such a system may belimited by the size of the incoupling prism 102.

Smart glasses superimpose image information for the user onto the user'sfield of view. In general, a distinction can be made between smartglasses for virtual reality and smart glasses for augmented reality,abbreviated as AR. In the case of smart glasses for virtual reality, areal environment is able to be masked and replaced with a virtual world.In the case of smart glasses for an augmented reality, virtual imagecontents are able to be superimposed onto the real environment. AR smartglasses may thus be configured in transparent or partially transparentform, for example. Possible application areas of AR smart glasses, forexample, are sports glasses for displaying the speed, navigation data,the step frequency or pulse beat; safety glasses for workshops; glassesor helmets in the context of driver-assistance or navigation systems;safety glasses for the display of instructions, operating instructionsor cable wiring; as well as glasses for home applications, e.g., for thedisplay of a virtual control button or a cooking recipe.

AR smart glasses may be realized as an NTE display or as a retinal-scandisplay, in short: RSD. In the case of NTE displays, a real image isgenerated in very close proximity to the eye of the observer, e.g., withthe aid of a micro-display, and viewed via an optics system, e.g., amagnifying glass. FIG. 1 shows one example of such a system. The virtualimage appears to the eye at a certain distance and will come into focusonly when the eye focuses to this distance.

FIG. 2 shows a schematic illustration of a method of functioning of anear-to-eye display 200 of smart glasses. In this case, a micro-display202 is viewed via a deflection optics system and a lens. In contrast tothe system illustrated in FIG. 1, the coupling of the image into the eyeis not realized with the aid of an additional optical element in frontof the eyeglass lens in this instance but using a light conductor withinthe eyeglass lens. In addition, incoupling and decoupling elements 204,in this case, holograms, are integrated. The space required byincoupling and decoupling elements 204 depends on the desired field ofview.

In the case of retinal-scan displays, the image is written directly ontothe retina. At no point in time does the image therefore exist outsidethe eye.

To be perceivable by the eye, the exit pupil of the system mustspatially overlap with the entry pupil of the eye.

FIG. 3 shows a diagram to illustrate a visual acuity 900, plotted on they-axis in this instance, as a function of an angle plotted on an opticalaxis, i.e. on the x-axis in this case. The highest density of sensorycells is located in the region of what is referred to as the macula ofthe eye, and the highest visual acuity is achieved in its center, whichis known as the fovea centralis or fovea. As can be gathered from FIG.3, the range of sharp sight is very limited. The visual acuity drops to30 percent of its maximum value within a mere plus/minus 5 degrees. Inorder to let the range of sharp sight appear larger, the human eyesubconsciously moves a few times per second in order to image arespective other region of the environment on the fovea.

FIG. 4 shows a schematic illustration of smart glasses 1000 having aprojection device according to an exemplary embodiment. Smart glasses1000 include a projection device 1002 having an image-generation unit1004, and a deflection element 1008, which is integrated into aneyeglass lens 1006 of smart glasses 1000 by way of example.Image-generation unit 1004 is configured to generate a first ray oflight 1010 representing first image information, or a corresponding beamof rays, as well as a second ray of light 1012 representing secondinformation, or a corresponding beam of rays and to steer them todeflection element 1008. The two items of image information differ withregard to the perceivable image sharpness, and the two items of imageinformation may represent one and the same image content. Deflectionelement 1008, e.g., a hologram layer or a composite of a plurality ofhologram layers, is configured to deflect first ray of light 1010 into afirst field of view 1014 of an eye 1016 of a wearer of smart glasses1000 and to deflect second ray of light 1012 into a second field of view1018 of eye 1016. The two fields of view 1014, 1018 are generallycompletely congruent, i.e. both fields of view cover the entire field ofview or eyeglass lens. According to one exemplary embodiment, deflectionelement 1008 extends across a large part of a surface of eyeglass lens1006 in order to cover the largest possible area of a field of view ofeye 1016. For example, first field of view 1014 is a central field ofview within which eye 1016 is able to perceive images with high visualacuity, and second field of view 1018 is a peripheral field of viewwithin which eye 1016 is able to perceive images only with low visualacuity.

According to one exemplary embodiment, image-generation unit 1004generates first ray of light 1010 in such a way that the first imageinformation has a greater perceivable image sharpness than the secondimage information represented by second ray of light 1012, so that theimage information featuring the greater image sharpness is displayedonly in the particular one of the two fields of view 1014, 1018 in whicheye 1016 is actually able to see clearly.

According to the exemplary embodiment shown in FIG. 4, smart glasses1000 also include an optical control unit 1020 for the actuation ofimage-generation unit 1004. For this purpose, control unit 1020transmits a corresponding control signal 1022 to image-generation unit1004, image-generation unit 1004 being configured to generate first rayof light 1010 and second ray of light 1012 using control signal 1022.

Depending on the exemplary embodiment, image-generation unit 1004 orcontrol unit 1020 may be fastened to a frame of smart glasses 1000.

FIG. 5 shows a schematic illustration of a projection device 1002according to an exemplary embodiment, e.g., a projection device asdescribed in the previous text with the aid of FIG. 4. In this case, eye1016 is offered sharp image information in first field of view 1014,which is a central field of view in this case. Since this central fieldof view comes to lie in different locations on deflection element 1008,which in this case is a holographic optical element, for different eyepositions of eye 1016, it is exemplarily subdivided into a first angularrange 1100, a second angular range 1102, and a further angular range1104, each one of the three angular ranges being allocated a particulareye position of eye 1016. According to this exemplary embodiment, thethree angular ranges are configured to sharply display a field of viewof 16 degrees in each case. Projection device 1002, for instance, isconfigured to display the remaining second field of view 1018 via afurther eye box having its own light source and own deflection element,e.g., a further holographic optical element. The further eye box has acertain minimum size so that the pupil of eye 1016 lies within the eyebox in every eye position.

The illustration of angular ranges 1100, 1102, 1104 in the lower regionof eyeglass lens 1018 has been omitted for reasons of clarity.

The entire field of view is subdivided into individual subranges 1100,1102, 1104. In these subranges, the first image information is offeredvia a collimated, i.e., a non-divergent or barely convergent, ray oflight such as a laser beam. As described earlier, due to the small raydiameter, a relatively small eye box with theoretically clearlyperceivable image information comes about. A slight movement of the eyehas the result that the pupil is no longer hit. However, since the eyeis capable of truly sharp imaging only in a small range, the one smalleye box having a large angular range is subdivided into a plurality ofsmall eye boxes having a small angular range in each case, similar tosubranges 1100, 1102, 1104, as will be explained in greater detail inthe following text with the aid of FIG. 6. These multiple eye boxes arethen placed in such a way that they hit the pupil at the respectiveassociated eye positions. It is also possible that multiple eye boxessimultaneously overlap with the pupil. The first image information inthe individual eye boxes should therefore be displayed in a manner thatis shifted with respect to the other in such a way that no double imagesare produced. In this context it is important that all eye boxes withthe first image information are activated in a permanent andsimultaneous manner.

The second image information is also offered in the entire field ofview, but a divergent ray of light is used in this case. The hologramgenerates the divergence from the originally collimated laser beam. Thedivergent ray of light has two effects: First of all, a large eye box isgenerated (see FIG. 5), and secondly, the image information is notsharply imaged by the human eye without a correction lens. However, ifonly the peripheral field of view, which can image only withoutsharpness anyway, is then supplied with the second image information,the advantage of the large eye box is maintained. In this context it isimportant that the second image information is always deactivated in thecentral field of view so that it is not superimposed onto the sharpimage information. Since the central field of view shifts with the eyemovement, the eye movement should be tracked with the aid of eyetracking, and the second image information should be controlledaccordingly.

Depending on the exemplary embodiment, at least two of the three angularranges 1100, 1102, 1104 are disposed next to each other and placed insuch a way that they at least partially overlap.

Using projection device 1002, the field of view is divided into twofields, i.e. the first, which in this case is central field of view 1014featuring high acuity, and the second, in this case peripheral field ofview 1018 featuring low acuity. In this way the image display is adaptedto the physiology of the human eye.

The position of first field of view 1014 on the eyeglass lens or on thedeflection element 1008 disposed thereon depends on the eye position.Since the pupil of eye 1016 is located at different locations indifferent eye positions, multiple eye boxes are generated thatcorrespond to these eye positions. Three eye boxes for three differenteye or pupil positions are shown in FIG. 5 by way of example. Each eyebox covers an exemplary angular range of 16 degrees. To ensure that eye1016 receives corresponding image information for each eye position, theeye boxes are spatially disposed, for instance. One possible placementof the eye boxes is shown in FIG. 6. In order to achieve a cleantransition between the individual eye boxes that the eye is unable tonotice, projection device 1002 may be configured to generate the eyeboxes, in particular eye boxes that adjoin one another, in such a waythat the angular ranges overlap. Despite the overlap of the angularranges of the eye boxes, within geometrical limits it is still possibleto write the eye boxes onto one and the same hologram layer as thedeflection element in a spatially separated manner, as described in thefollowing text with the aid of FIGS. 13 and 14. As a matter ofprinciple, it is therefore possible to display all eye boxes illustratedin FIG. 6 using a single hologram layer and a single light source.

Projection device 1002, for example, may be combined with acorrection-optics system, such as it is used in glasses, for instance.The combinability with correction optics systems results from theability to apply the holographic optical systems on curved surfaces,e.g., ground eyeglass lenses.

For a true and distortion-free image display, the image-generation unitis configured to generate the first or the second ray of light in such away that an item of image information to be displayed will be perceivedas a geometrically correct image in every eye position. This isadvantageous in particular when the pupil of eye 1016 simultaneouslyviews a plurality of eye boxes, as is usually the case. Depending on theexemplary embodiment, a corresponding conversion of the image data takesplace, either in the image-generation unit itself, e.g., using amicrocontroller or FPGA, or externally, for instance in a mobile userterminal such as a cell phone.

Optionally, projection device 1002 includes more than one light sourceor more than one deflection element for generating the eye boxes infirst field of view 1014. More specifically, projection device 1002 isconfigured to write adjacent eye boxes onto different hologram layers asdeflection elements. In doing so, for example, only every second eye boxis written onto a first hologram layer, while the remaining eye boxesare written onto a second hologram layer. This makes it possible togenerate eye boxes that feature larger angular ranges. Additionally oralternatively, it is then possible to ensure a larger spatial safetydistance between the areas of the individual eye boxes on the hologramlayers.

According to an exemplary embodiment, projection device 1002 is used forthe display of monochromatic image information. However, by using lightsources of different colors, e.g., in the RGB range, it is also possibleto display color images with the aid of projection device 1002. Thenumber of required light sources and required deflection elements wouldtriple accordingly in such a case. However, in an effort to keep theinstallation space of such an RGB system small nevertheless, acombination of a plurality of light sources at the chip level isconceivable, such as via on-chip waveguides, for example.

The tracking of the eye positions that is required for this purpose iscarried out directly via an already installed laser scanner as theeye-position ascertainment unit, for instance. At least one of thealready installed light sources in the visible wavelength range or alsoa further light source in the invisible wavelength range, e.g., in theinfrared range, is used for this purpose. A back reading is carried outvia an optical transmission path, for example, i.e. possibly via amicromirror, or via a suitable detector installed at another location inthe system. Alternatively, the eye-position ascertainment unit includesa camera for detecting the eye positions.

The ascertainment of the gaze direction, i.e. the eye position, may alsobe carried out by measuring the eye background. For example, in thiscontext it may be exploited that a laser beam scans the eye backgroundfor the image generation. If an optical return channel is provided, thenan image of the eye background and the blood vessels that extend thereinis able to be generated. From the displacements of this image, as theyoccur during eye movements, the eye movement may be inferred in asimilar manner as in the case of an optical computer mouse, for example.

Using projection device 1002, for example, a laser beam is able to bewritten directly onto the retina of eye 1016. Thus, it is possible togenerate an image or video of the retina with the aid of projectiondevice 1002. This is realized, for example, by a corresponding backreading via the optical transmission path. With the aid of such asystem, the wearer of the smart glasses, for example, is able to begeometrically identified on the basis of a vein structure of the retina.Also conceivable would be the determination of a pulse beat as afunction of the pulsation of the veins that extend in the retina, or thedetermination of an oxygen saturation via a color of the blood flowingin the veins.

FIG. 6 shows a schematic representation of a system of eye boxes 1200,1204 for the display of image information with the aid of a deflectionelement according to an exemplary embodiment. Shown is an exemplarysystem of the eye boxes for a sharp display of first field of view 1014,which is the central field of view of eye 1016 in this case. Accordingto this exemplary embodiment, in addition to eye box 1200 for firstangular range 1100 and eye box 1202 for second angular range 1102, firstfield of view 1014 encompasses a plurality of further eye boxes 1204,which are disposed in a grid, which is a square grid in this instance,around the pupil of eye 1016.

Each one of these eye boxes covers a separate angular range of firstfield of view 1014. The angular ranges, especially those of adjacent eyeboxes, may overlap in this case. FIG. 8 illustrates such an overlap in aside view.

FIG. 7 shows a schematic representation of a correlation between anorientation of an eye 1016 and an image position on a deflection element1008 according to an exemplary embodiment. For example, deflectionelement 1008 is part of a projection device as it was described in thepreceding text with the aid of FIGS. 4 through 6. Shown is the eyeglasslens together with a holographic optical element as deflection element1008. According to this exemplary embodiment, deflection element 1008 isconfigured to fade in an image point in the field of view at 10 degrees.

If eye 1016 is focused on β=0°, for example, then the image point isgenerated at α=10°, i.e. the image point is imaged at the location a ondeflection element 1008.

However, if eye 1016 is focused on β=10°, then the image point isgenerated at α=0°, i.e. the image point is imaged at location b ondeflection element 1008. As a result, the same image information isgenerated at two different locations on deflection element 1008.

FIG. 8 shows a schematic illustration of two overlapping angular rangesfor the display of image information with the aid of a deflectionelement 1008 according to an exemplary embodiment. Shown are two eyeboxes, spatially separated from each other on deflection element 1008,with the associated eye positions of eye 1016. According to thisparticular exemplary embodiment, the overlap is created when the eye isfocused on β=0° or on β=10°. Although the eye boxes are spatiallyseparated from each other on deflection element 1008, the two angularranges 1100, 1102 overlap.

FIG. 9 shows a flow diagram of a method 1500 according to an exemplaryembodiment. For example, method 1500 may be carried out using aprojection device as previously described on the basis of FIGS. 4through 8. In doing so, in a step 1510, the first and the second ray oflight or corresponding beams of light are generated by theimage-generation unit. In a further step 1520, the first ray of light orthe first beam of light is deflected with the aid of the deflectionelement in such a way that the first image information is displayedwithin the first field of view. In a corresponding manner, the secondray of light is deflected in order to display the second imageinformation within a second field of view.

FIG. 10 shows a schematic representation of a control unit 1020according to an exemplary embodiment, such as a control unit asdescribed previously on the basis of FIG. 4. Control unit 1020 includesa generation unit 1610, which is configured to generate control signal1022 for the control of the image-generation unit.

Depending on the exemplary embodiment, control unit 1020 is configuredas an external unit or as a unit that is integrated into theimage-generation unit.

If an exemplary embodiment includes an “and/or” linkage between a firstfeature and a second feature, then this should be read as indicatingthat the exemplary embodiment according to one specific embodimentincludes both the first and the second feature, and according to afurther specific embodiment, it includes either only the first featureor only the second feature.

What is claimed is:
 1. A projection device for smart glasses,comprising: an image-generation unit to generate at least one first rayof light representing first image information, and a second ray of lightrepresenting second image information, the first ray of light and thesecond ray of light differing from each other with regard to a beamdivergence, and the first image information and the second imageinformation differing from each other with regard to a perceivable imagesharpness; and at least one deflection element to display the firstimage information within a first field of view of an eye using the firstray of light, and to display the second image information within asecond field of view of the eye using the second ray of light, thesecond field of view being located outside the first field of view;wherein the image-generation unit is configured to generate the firstray of light and the second ray of light so that the first imageinformation has a greater perceived image sharpness than the secondimage information, the deflection element being configured to at leastone of: (i) display the first image information within a central fieldof view of the eye as the first field of view, and/or (ii) display thesecond image information within a peripheral field of view of the eye asthe second field of view; and wherein the first image information andthe second information represent exactly the same image content as oneanother but at the differing perceived image sharpness relative to oneanother.
 2. The projection device of claim 1, wherein the deflectionelement is configured to display the first image information within afirst angular range, allocated to a first position of the eye, of thefirst field of view and/or within a further angular range, allocated toa further position of the eye, of the first field of view.
 3. Theprojection device of claim 2, wherein the deflection element isconfigured to display the first image information within an angularrange as the first angular range, which is disposed adjacent to thesecond angular range or which at least partially overlaps with thesecond angular range.
 4. The projection device of claim 1, wherein thedeflection element is configured to display the first image informationwithin at least one further angular range, allocated to a furtherposition of the eye, of the first field of view.
 5. The projectiondevice of claim 1, wherein the deflection element has at least onehologram layer for deflecting at least one of the first ray of light andthe second ray of light.
 6. The projection device of claim 1, furthercomprising: at least one further deflection element and a further lightsource, the further deflection element being configured to display thefirst image information within the first field of view, using the ray oflight of the further light source, the deflection element beingconfigured to generate at least one first eye box for perceiving thefirst image information within the first field of view, and the furtherdeflection element being developed to generate at least one second eyebox for perceiving the first image information within the first field ofview, the first eye box and the second eye box being disposed adjacentto each other.
 7. The projection device of claim 1, further comprising:an eyeglass lens, the deflection element being realized as part of theeyeglass lens and/or being applied on the eyeglass lens.
 8. Theprojection device of claim 7, wherein the deflection element extendsacross at least a main part of a surface of the eyeglass lens.
 9. Theprojection device of claim 1, further comprising: an eye-positionascertainment unit to ascertain an eye position of the eye, theimage-generation unit being configured to generate the first ray oflight and/or the second ray of light as a function of the eye position,and/or the eye-position ascertainment unit being configured to ascertainthe eye position using a laser.
 10. The projection device of claim 1,wherein the image-generation unit is configured to generate the firstray of light and/or the second ray of light so that the first imageinformation and/or the second image information represents at least atwo-color image.
 11. The projection device of claim 1, wherein theimage-generation unit is configured to generate the first ray of lightand/or the second ray of light so that the first image informationand/or the second image information represents a multi-color image. 12.The projection device of claim 1, wherein each of the first ray of lightand the second ray of light covers an entire field of view.
 13. A methodfor displaying image information with a projection device, the methodcomprising: generating at least one first ray of light and a second rayof light, wherein the projection device projection device includes animage-generation unit to generate the at least one first ray of lightrepresenting first image information, and the second ray of lightrepresenting second image information, the first ray of light and thesecond ray of light differing from each other with regard to a beamdivergence, and the first image information and the second imageinformation differing from each other with regard to a perceivable imagesharpness, and at least one deflection element to display the firstimage information within a first field of view of an eye using the firstray of light, and to display the second image information within asecond field of view of the eye using the second ray of light, thesecond field of view being located outside the first field of view; anddeflecting the first ray of light to display the first image informationwithin the first field of view, and deflecting the second ray of lightto display the second image information within the second field of view;wherein the image-generation unit generates the first ray of light andthe second ray of light so that the first image information has agreater perceived image sharpness than the second image information,wherein the deflecting includes: (i) displaying the first imageinformation within a central field of view of the eye as the first fieldof view, and/or (ii) displaying the second image information within aperipheral field of view of the eye as the second field of view; andwherein the first image information and the second information representexactly the same image content as one another but at the differingperceived image sharpness relative to one another.
 14. The method asrecited in claim 13, wherein each of the first ray of light and thesecond ray of light covers an entire field of view.
 15. A control unitfor displaying image information with a projection device, comprising: acontrol device configured to perform the following: generating at leastone first ray of light and a second ray of light, wherein the projectiondevice projection device includes an image-generation unit to generatethe at least one first ray of light representing first imageinformation, and the second ray of light representing second imageinformation, the first ray of light and the second ray of lightdiffering from each other with regard to a beam divergence, and thefirst image information and the second image information differing fromeach other with regard to a perceivable image sharpness, and at leastone deflection element to display the first image information within afirst field of view of an eye using the first ray of light, and todisplay the second image information within a second field of view ofthe eye using the second ray of light, the second field of view beinglocated outside the first field of view; and deflecting the first ray oflight to display the first image information within the first field ofview, and deflecting the second ray of light to display the second imageinformation within the second field of view; wherein theimage-generation unit generates the first ray of light and the secondray of light so that the first image information has a greater perceivedimage sharpness than the second image information, wherein thedeflecting includes: (i) displaying the first image information within acentral field of view of the eye as the first field of view, and/or (ii)displaying the second image information within a peripheral field ofview of the eye as the second field of view; and wherein the first imageinformation and the second information represent exactly the same imagecontent as one another but at the differing perceived image sharpnessrelative to one another.
 16. The control unit as recited in claim 15,wherein each of the first ray of light and the second ray of lightcovers an entire field of view.
 17. A non-transitory computer readablemedium on which is stored a computer program, including program code fordisplaying image information with a projection device, the computerprogram, when executed by a processor, causing the processor to perform:generating at least one first ray of light and a second ray of light,wherein the projection device projection device includes animage-generation unit to generate the at least one first ray of lightrepresenting first image information, and the second ray of lightrepresenting second image information, the first ray of light and thesecond ray of light differing from each other with regard to a beamdivergence, and the first image information and the second imageinformation differing from each other with regard to a perceivable imagesharpness, and at least one deflection element to display the firstimage information within a first field of view of an eye using the firstray of light, and to display the second image information within asecond field of view of the eye using the second ray of light, thesecond field of view being located outside the first field of view; anddeflecting the first ray of light to display the first image informationwithin the first field of view, and deflecting the second ray of lightto display the second image information within the second field of view;wherein the image-generation unit generates the first ray of light andthe second ray of light so that the first image information has agreater perceived image sharpness than the second image information,wherein the deflecting includes: (i) displaying the first imageinformation within a central field of view of the eye as the first fieldof view, and/or (ii) displaying the second image information within aperipheral field of view of the eye as the second field of view; andwherein the first image information and the second information representexactly the same image content as one another but at the differingperceived image sharpness relative to one another.
 18. Thenon-transitory computer readable medium as recited in claim 17, whereineach of the first ray of light and the second ray of light covers anentire field of view.